Impairments Impairments - Fixed Assets and Other Table (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	$ 26	$ 6	$ 417	$ 44
Natural Gas Compressor [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	0	0	0	20
Buildings and land [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	2	0	2	7
Other [Member]
Property, Plant and Equipment [Line Items]
Impairments of fixed assets and other	$ 24	$ 6	$ 415	$ 17